Automatic pump control device

Abstract

An automatic pump control device for an injection pump used to inject fluid (typically methanol) into oil or natural gas wells to prevent freezing. The device enables the pump to operate at rates as low as one full stroke per 1.5 minutes (i.e., 0.67 stroke/min), substantially slower than current rates of approximately fifteen strokes per minute. The device comprises a main body; an extension air pilot; a retraction air pilot; a toggle mechanism that actuates the extension air pilot to extend the pump piston, that at the end of the extension stroke actuates a retraction air pilot to retract the pump piston, and that automatically continues the two stroke cycle; a drive mechanism for driving the toggle mechanism; an overstroke mechanism to prevent over driving the retraction air pilot at the end of its stroke; an optional stroke speed adjustment valve; a circuit to circulate and transport a gas; and piston, spool, and sleeve for switching the path of the gas. The automatic pump control device operates over a wide range of flow rates and pressure ranges, thus enabling installation of the automatic pump control device to virtually all manufacturers' injection pumps.

1. An automatic control device for an injection pump used to inject a fluid into a source of a pressurized gas; the injection pump comprising a shaft that extends and refracts, and a linkage mounted to the shaft for actuating the injection pump; the linkage having first and second portions respectively corresponding to extension and refraction of the shaft, the automatic control device comprising:
 a) a two position toggle valve, driven by the pressurized gas, to pulse between first and second positions that correspond to the extension and retraction of the shaft, respectively; 
 b) a driver, coupled to the toggle valve, having first and second single-point contact surfaces corresponding to the first and second portions of the linkage of the injection pump; and 
 c) an overstroke mechanism to prevent overdriving the injection pump beyond full extension; 
 in which the toggle valve pulses in a two-stroke cycle between the first and second positions to couple the respective first and second single-point contact surfaces of the driver to the respective first and second portions of the linkage, thereby alternatively causing the extension and retraction of the shaft of the injection pump. 
 
     
     
       2. The device of  claim 1 , further comprising an adjustment valve for adjustment of stroke speed. 
     
     
       3. The device of  claim 1 , in which the injection pump injects a fluid into a fossil fuel well. 
     
     
       4. A method of controlling injection of a fluid by an injection pump into a source of a pressurized gas, comprising:
 a) using the pressurized gas to power a two position toggle valve to automatically pulse in a two-stroke cycle corresponding to first and second positions of the injection pump; and 
 b) preventing overdriving of the injection pump beyond full extension. 
 
     
     
       5. The method of  claim 4 , further comprising coupling respective first and second single-point contact surfaces of a driver acting in the two-stroke cycle to respective first and second portions of a linkage coupled to the injection pump. 
     
     
       6. The method of  claim 5 , in which the linkage is coupled to a shaft of the injection pump. 
     
     
       7. The method of  claim 4 , further comprising adjusting stroke speed. 
     
     
       8. The method of  claim 4 , in which the injection pump injects a fluid into a fossil fuel well.